The project examines the influence of schooling on cognitive development by exploiting a "natural experiment", termed school cutoff. Each year school boards proclaim that those children whose birth-dates precede some specified date will be allowed to go to kindergarten or grade one, while other children who just miss the cutoff will not be allowed entry. By choosing children whose birth-dates cluster closely on--either side of the cutoff date, two groups of children can be effectively equated on some target psychological skill or process. Comparing the degree of change in the target skill from beginning to end of the school year (pre-post design) in the children who just make versus miss the cutoff permits direct assessment of the impact of the schooling experience an growth of that skill. A series of studies using this methodology will examine the influence of grade one schooling on a broad range of cognitive skills, including memory strategies, language processing, causal reasoning, narrative comprehension, logical operations, and arithmetic problem-solving. Findings from these studies will (1) yield greater understanding of the power of the schooling experience to enhance cognitive growth; (2) evaluate how extensive or limited is schooling's influence an basic cognitive skills; (3) establish the fruitfulness of the school cutoff methodology in elucidating important sources of change in cognitive processing during the early school years.